The overall objective of this work is to prepare a set of monoclonal antibodies that label discrete subpopulations of cells in the visual system. These antibodies will be used to study the in vivo development of the cells of the visual system, in particular the embryologic relationships of the various subpopulations with each other. The antibodies will also be used to prepare and study isolated cells, particularly with respect to their neurotransmitters and electrical properties. In addition, the antibodies will be used to study cells of the visual system in tissue culture. In conjunction with electrophysiological techniques, the antibodies will be used to study the specificity and pharmacology of synapse formation in vitro. To prepare the monoclonal antibodies purified plasma membrane from specific regions of the visual system, or a glycoprotein fraction from the membrane, will be used to immunize mice. Spleen cells will be taken from mice mounting an adequate immune response and fused with a mouse plasmacytoma. Hybrids will be selected by standard techniques and those secreting antibody detected by using a radioactive binding assay. The cell types within a tissue that react with a given antibody will be determined by using immunohistochemical analysis of tissue sections. The development of the cell types in vivo will be studied by using tissue from animals of various ages. Cells will be isolated from young or adult animals by dissociation, labeling with specific antibody and separation using either a fluorescence-activated cell sorter or density gradients. Synaptic interactions between defined cell types in culture will be monitored by intracellular recording and compared with the types of interaction found in vivo by other anatomical and electrophysiological studies.